Analysis on the enhanced hole concentration in p-type GaN grown by indium-surfactant-assisted Mg delta doping

We have investigated the influence of indium surfactant on the hole-concentration enhancement in Mg-delta-doped p-type GaN grown at 920 degrees C. The hole concentration can be effectively enhanced from 7.8 x 10(17) cm(-3) to 1.5 x 10(18) cm(-3) when introducing the indium surfactant into the delta-doping process. Analysis by secondary ion mass spectroscopy and low-temperature photoluminescence results indicates that the increase of hole concentration is primarily contributed from the improved Mg incorporation and the suppressed N vacancy induced by the indium surfactant, while the contribution from unintentional C, Si, and O impurities and Ga-vacancy-related defects can be ruled out. On the other hand, it is shown that the acceptor activation energy, deduced from the temperature-dependent photoluminescence, is decreased by indium surfactant, which is another factor accounting for the enhanced hole concentration. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim